chemistry journal of moldova

Chemistry Journal of Moldova. M. Gonta General, et al./Chem.J.Mold. Industrial and 2008, Ecological 3 (1), 118-126 Chemistry. 2008, 3 (1), 118-126ESTABLISHMENT OF THE ANTIOXIDANT/ANTIRADICAL ACTIVITYOF THE INHIBITORS USING THE DPPH – RADICALMaria Gonta a *, Gheorghe Duca b , Diana Porubin aaState University of Moldova, 60 Mateevici str., Chisinau, Republic of MoldovabThe Academy of Sciences of Moldova, 1 Stefan cel Mare blvd., Chisinau, Republic of Moldova* Corresponding author: Phone: (373 22) 57-75-53, Email: mvgonta@yahoo.comAbstract. This research paper presents the results of the investigation of antioxidant activities of various inhibitors,which are constituents of winery products: quercitin, rezveratrol, dihydroxyfumaric acid. Also, the antioxidantactivity of tartaric and dihydroxyfumaric (DFH 4) acids derivatives has been determined: sodium dihydroxyfumarate,dimethylic ester of DFH 4and dimethylic ester of tartaric acid. The enotannin extracts obtained from grape seedshave been evaluated: the non-oxidized enotannin extract Eneox and the oxidized one -Enoxil. For the determinationof the antioxidant/antiradical activity the 2,2-diphenil-1-picrylhidrazil (DPPH) radical was used, which has theabsorption maxima at 517 nm. The efficient concentration EC 50, the stoichiometric value of the antioxidant andthe free radical, the antiradical power (1/EC 50) and the number of moles of DPPH-radical reduced by one mole ofinhibitor have been calculated for all investigated inhibitors. It was found that catechin, quercitin and DFH 4exhibitthe highest inhibition rate.Keywords: antioxidant activity, DPPH radical, inhibition rate, natural inhibitors from secondary winery materialsOverviewNumerous practical and epidemiological studies have confirmed that the micronutrients, thus the antioxidantsexisting in aliments, are able to inhibit the cancerigenesis through their influence on the molecular level, during theinitiation, promotion and progression stages.In recent times, the most studied compounds were the polyphenols, which are constituents of the plants.The antioxidant activity of the polyphenols is controlled by the presence of the hydroxylic groups in the B ringin 3’ and 4’ positions and in a lesser degree, by the presence of the hydroxylic group from the C ring in 4’ position.The flavonols, especially catechin, quercitin, kaempherol and their glucosides are elements of the black andgreen teas [5] and red wine [5]. The diets rich in vegetables and fruits, especially in grapes, protect against heartdiseases, various forms of cancer [7, 8], methemoglobinemy, and display anti-inflammatory, as well as antimutageniceffects [9]. These protective upshots were attributed, in a great measure, to the antioxidants that include flavonoids aswell as carotenoids and vitamins C and B.The majority of the polyphenolic constituents from products (flavonols – like quercitine and kaempherol, flavones– like luteolin, flavonones – like catechin, anthocyanidin, for example, cyanidin and malvidin and their glycosides)presents high efficiency, in comparison to the nutrient antioxidants: vitamins C, E, -carotene, that are easily adsorbedin the intestines [10].The grapes and the wine contain high concentrations of antioxidants. Based on the study of the overall antioxidantactivity of the red wine, we concluded that 54,76% is determined by the contribution of catechin and epicatechin, thatform approximately 63,54% of the phenolic constituents (191 and 82 mg/l, correspondingly) [10].Fig.1. Chemical structure of the catechins present in tea and wine [5]. Catechin-(R 1- OH, R 2- H), gallocatechin-(R 1- OH, R 2- OH), catechingallate (R 1- GA, R 2- H), gallocatechingallate (R 1- GA, R 2- OH)118